Students who have normal intelligence can, on an average, score around sixty per cent marks. If they are not able to score that, it may be due to problems in their cognition, emotional management or study behaviour.
If the student learns to make use of his/her memory, concentration, learning and calculation abilities in a faulty manner, then he/she is likely to have difficulties with learning.
Also, if the student does not develop good learning behaviour it can adversely affect his/her studies. Example: taking frequent breaks, passive learning, sitting to study without an objective in mind, easily getting distracted, poor ability to perform responsibilities etc.